Instant messaging services have become popular for communicating quickly with other people. Generally, an instant messaging service enables a user to easily exchange textual messages with a friend or co-worker. In a such a messaging system, a user typically maintains a list of possible contact names in a list. The list includes a visual or audio indicator that informs the user which of the contacts are currently active on the messaging service. In a similar manner, when the user is on the messaging system, that user will be identified to others as being available to receive a communication.
Commercial examples of such instant messaging services include ICQ from ICQ, Inc., AOL's Instant Messenger and Yahoo's Messenger. Instant messaging may utilize a software program written for that purpose, or may be conducted through a standard web browser such as Microsoft's Internet Explorer or Netscape's Netscape browser. Instant messages are typically shorter and more conversational than electronic mail messages, due to the more-interactive nature of instant messaging.
An instant messaging system typically notifies users of changes in state of one or more other users. That is, a user can determine if another user is currently connected to the instant messaging system, and can determine whether that user changes his or her connection state. When a user logs into the instant messaging system, that user transmits presence information to the instant messaging system, announcing his or her presence on the system. When that user logs out of the instant messaging system, or terminates the connection to the instant messaging system, the presence information for that user is updated to show that the user is offline.
Instant messaging is presently used on wireless communications devices, such as wireless telephones, personal digital assistants (PDAs), laptop computers, and other hardware. To participate in an instant messaging service, the user's wireless communications device is connected by a voice channel to a wireless communications network. Instant message data travels over that voice channel, in the same manner as any data traverses a voice channel between the wireless communications device and the wireless communications network. Such transmission of data on a wireless voice channel may be referred to as a “data connection” in this document.
While the user can participate in instant messaging through a wireless data connection, the wireless data connection costs the user money in airtime fees, and can deplete the battery or batteries in the wireless communications device as quickly as a voice call. Further, the wireless data connection utilizes a channel on the wireless communications network, thereby consuming significant network resources for relatively small amounts of data.